Some deicing systems and methods used for deicing snow and ice-covered aircraft surfaces use an apparatus that sprays large quantities of deicing fluids onto the aircraft surfaces. Typically, this has been accomplished by spraying a heated antifreeze fluid (e.g., a glycol and water mixture) onto the iced surfaces of the aircraft, together with a large quantity of compressed air. An example includes the system disclosed in U.S. Pat. No. 5,244,168, the disclosure which is hereby incorporated by reference in its entirety, where a nozzle mixes pressurized air and deicing fluid to provide a spray pattern for application to the aircraft to deice the aircraft.
Other systems separate the glycol and water mixture from the compressed air and include a separate nozzle for discharging compressed air by providing a forced air deicing system having a powerful compressed air source. Typically, these systems include a vehicle frame, such as the chassis of a truck, having a boom with one end mounted on the vehicle frame and a free end. An operator cab is positioned at the free end of the boom and a deicer air jet nozzle is connected at the free end of the boom, typically mounted on the operator cab for operator control.
Many of these systems use very powerful jet engine air start units. The air exits the nozzle at a temperature of 300.degree. F. to 400.degree. F. above ambient. As a result, some of the ice and snow is melted and can migrate into crevices on the aircraft. The aircraft acts as a heat sink because the large mass of the aircraft remains at subfreezing temperatures. Thus, sensitive sensors and critical trailing edge flaps may become frozen and ineffective.
Typically, this type of compressor is capable of 300 to 500 horsepower and provide 300 to 400 pounds a minute of compressed air. The units are very inefficient producing unnecessary hot air and excessive noise. Additionally, these systems are very heavy and must be positioned near the vehicle frame, a long distance from the operator cab carrying an air jet nozzle. As a result, long tubes must extend from the vehicle frame along the boom to the operator cab where the nozzles are located. These long runs from the compressor can cause thermodynamic and pneumatic deficiencies.
Also, any system that injects fluid at high pressure into the air stream has a drawback because the fluid could act as a cutting medium and damage aircraft surfaces. Therefore, it is essential in some instances to keep a great distance from the aircraft to avoid damaging the aircraft with the high pressure fluid, thus making the forced air system ineffective.